Messages in this thread | | | Date | Fri, 31 Aug 2012 11:34:31 -0700 | From | Josh Triplett <> | Subject | Re: [PATCH tip/core/rcu 13/15] rcu: Move TINY_PREEMPT_RCU away from raw_local_irq_save() |
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On Thu, Aug 30, 2012 at 11:56:26AM -0700, Paul E. McKenney wrote: > From: "Paul E. McKenney" <paul.mckenney@linaro.org> > > The use of raw_local_irq_save() is unnecessary, given that local_irq_save() > really does disable interrupts. Also, it appears to interfere with lockdep. > Therefore, this commit moves to local_irq_save().
It looks like the non-raw versions also include tracing, which typically has recursive dependency problems with RCU. Can all of these call sites safely call into tracing without recursing back into RCU?
- Josh Triplett
> Reported-by: Fengguang Wu <fengguang.wu@intel.com> > Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> > Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Tested-by: Fengguang Wu <fengguang.wu@intel.com> > --- > kernel/rcutiny_plugin.h | 10 +++++----- > 1 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h > index 918fd1e..3d01902 100644 > --- a/kernel/rcutiny_plugin.h > +++ b/kernel/rcutiny_plugin.h > @@ -278,7 +278,7 @@ static int rcu_boost(void) > rcu_preempt_ctrlblk.exp_tasks == NULL) > return 0; /* Nothing to boost. */ > > - raw_local_irq_save(flags); > + local_irq_save(flags); > > /* > * Recheck with irqs disabled: all tasks in need of boosting > @@ -287,7 +287,7 @@ static int rcu_boost(void) > */ > if (rcu_preempt_ctrlblk.boost_tasks == NULL && > rcu_preempt_ctrlblk.exp_tasks == NULL) { > - raw_local_irq_restore(flags); > + local_irq_restore(flags); > return 0; > } > > @@ -317,7 +317,7 @@ static int rcu_boost(void) > t = container_of(tb, struct task_struct, rcu_node_entry); > rt_mutex_init_proxy_locked(&mtx, t); > t->rcu_boost_mutex = &mtx; > - raw_local_irq_restore(flags); > + local_irq_restore(flags); > rt_mutex_lock(&mtx); > rt_mutex_unlock(&mtx); /* Keep lockdep happy. */ > > @@ -991,9 +991,9 @@ static void rcu_trace_sub_qlen(struct rcu_ctrlblk *rcp, int n) > { > unsigned long flags; > > - raw_local_irq_save(flags); > + local_irq_save(flags); > rcp->qlen -= n; > - raw_local_irq_restore(flags); > + local_irq_restore(flags); > } > > /* > -- > 1.7.8 >
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